DESCRIPTION: This project will create a nationally representative 1-in-100 Public Use Microdata Sample (PUMS) of the 1900 census of the United States population to be disseminated through the National Archives, the Inter-University Consortium for Political and Social Research, and via the Internet. Preparation of the 1900 PUMS involves seven steps: 1)transcribe census information on approximately 783,000 individuals drawn from microfilm of original enumerators' manuscripts; 2) develop data dictionaries to convert each census inquiry into a format compatible with existing census microdata files; 3) evaluate sample quality through consistency checks, random blind verification, and comparison with aggregate census tabulations; 4) edit missing, illegible, and inconsistent data items using logical inference and hot-deck allocation techniques; 5) create new variables describing family relationships, household composition, occupational status, and city and county level characteristics; 6) prepare documentation on sampling and data processing procedures, a procedural history of the 1900 census, and a user's guide; and 7) integrate the sample into the Integrated Public Use Microdata Series (IPUMS). As the earliest surviving modern census, the 1900 census provides a baseline for measuring the monumental social changes of the twentieth century. Variables available for the first time in1900 reflect some of the social concerns at the turn of the century: year of immigration, years in the United States, citizenship status, ability to speak English, children ever-born, children surviving, duration of marriage, farm residence, home ownership, mortgage status, number of months attending school, and date of birth. There are numerous key areas of research available through the 1900 sample including child mortality, fertility analysis, and ethnicity and immigration. In addition, a planned oversample of Native Americans will allow new opportunities for quantitative studies of American Indian demography and social structure.